The euphoria that comes after one is relieved of an enormous poo. That relief that you feel, then the feeling of weighing less. This especially occurs after you've been holding it in for an extended period of time.

A: Dude, you look really happy right now. Why is that?
B: I'm in an extreme sense of poopulation.

Or:

Alex: Molly, say that Russia's POPULATION is higher, not their poopulation, I doubt that that is included on the chart.
Molly: -laughs- Good point.